Do not torn down the system when getting invalid status from a TPM chip. This can happen when panic-on-warn is used.
In addition, print out the value of TPM_STS.x instead of "invalid status". In order to get the earlier benefits for forensics, also call dump_stack().
Link: https://lore.kernel.org/keyrings/YKzlTR1AzUigShtZ@kroah.com/ Fixes: 55707d531af6 ("tpm_tis: Add a check for invalid status") Cc: stable@vger.kernel.org Cc: Hans de Goede hdegoede@redhat.com Cc: Greg KH greg@kroah.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org ---
v2: Dump also stack only once.
drivers/char/tpm/tpm_tis_core.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 55b9d3965ae1..ce410f19eff2 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -188,21 +188,33 @@ static int request_locality(struct tpm_chip *chip, int l) static u8 tpm_tis_status(struct tpm_chip *chip) { struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev); - int rc; + static unsigned long klog_once; u8 status; + int rc;
rc = tpm_tis_read8(priv, TPM_STS(priv->locality), &status); if (rc < 0) return 0;
if (unlikely((status & TPM_STS_READ_ZERO) != 0)) { - /* - * If this trips, the chances are the read is - * returning 0xff because the locality hasn't been - * acquired. Usually because tpm_try_get_ops() hasn't - * been called before doing a TPM operation. - */ - WARN_ONCE(1, "TPM returned invalid status\n"); + if (!test_and_set_bit(BIT(0), &klog_once)) { + /* + * If this trips, the chances are the read is + * returning 0xff because the locality hasn't been + * acquired. Usually because tpm_try_get_ops() hasn't + * been called before doing a TPM operation. + */ + dev_err(&chip->dev, "invalid TPM_STS.x 0x%02x, dumping stack for forensics\n", + status); + + /* + * Dump stack for forensics, as invalid TPM_STS.x could be + * potentially triggered by impaired tpm_try_get_ops() or + * tpm_find_get_ops(). + */ + dump_stack(); + } + return 0; }
On Mon, May 31, 2021 at 08:34:27AM +0300, Jarkko Sakkinen wrote:
Do not torn down the system when getting invalid status from a TPM chip. This can happen when panic-on-warn is used.
In addition, print out the value of TPM_STS.x instead of "invalid status". In order to get the earlier benefits for forensics, also call dump_stack().
Link: https://lore.kernel.org/keyrings/YKzlTR1AzUigShtZ@kroah.com/ Fixes: 55707d531af6 ("tpm_tis: Add a check for invalid status") Cc: stable@vger.kernel.org Cc: Hans de Goede hdegoede@redhat.com Cc: Greg KH greg@kroah.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org
v2: Dump also stack only once.
Huh?
drivers/char/tpm/tpm_tis_core.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 55b9d3965ae1..ce410f19eff2 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -188,21 +188,33 @@ static int request_locality(struct tpm_chip *chip, int l) static u8 tpm_tis_status(struct tpm_chip *chip) { struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
- int rc;
- static unsigned long klog_once; u8 status;
- int rc;
rc = tpm_tis_read8(priv, TPM_STS(priv->locality), &status); if (rc < 0) return 0; if (unlikely((status & TPM_STS_READ_ZERO) != 0)) {
/** If this trips, the chances are the read is* returning 0xff because the locality hasn't been* acquired. Usually because tpm_try_get_ops() hasn't* been called before doing a TPM operation.*/WARN_ONCE(1, "TPM returned invalid status\n");
if (!test_and_set_bit(BIT(0), &klog_once)) {
Odd whitespace...
Anyway, why? Isn't this what the ratelimit stuff should give you? How badly is this being tripped so much so that you need to only do this once per entire system and not per-device?
thanks,
greg k-h
On Mon, May 31, 2021 at 07:50:41AM +0200, Greg KH wrote:
On Mon, May 31, 2021 at 08:34:27AM +0300, Jarkko Sakkinen wrote:
Do not torn down the system when getting invalid status from a TPM chip. This can happen when panic-on-warn is used.
In addition, print out the value of TPM_STS.x instead of "invalid status". In order to get the earlier benefits for forensics, also call dump_stack().
Link: https://lore.kernel.org/keyrings/YKzlTR1AzUigShtZ@kroah.com/ Fixes: 55707d531af6 ("tpm_tis: Add a check for invalid status") Cc: stable@vger.kernel.org Cc: Hans de Goede hdegoede@redhat.com Cc: Greg KH greg@kroah.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org
v2: Dump also stack only once.
Huh?
drivers/char/tpm/tpm_tis_core.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 55b9d3965ae1..ce410f19eff2 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -188,21 +188,33 @@ static int request_locality(struct tpm_chip *chip, int l) static u8 tpm_tis_status(struct tpm_chip *chip) { struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
- int rc;
- static unsigned long klog_once; u8 status;
- int rc;
rc = tpm_tis_read8(priv, TPM_STS(priv->locality), &status); if (rc < 0) return 0; if (unlikely((status & TPM_STS_READ_ZERO) != 0)) {
/** If this trips, the chances are the read is* returning 0xff because the locality hasn't been* acquired. Usually because tpm_try_get_ops() hasn't* been called before doing a TPM operation.*/WARN_ONCE(1, "TPM returned invalid status\n");
if (!test_and_set_bit(BIT(0), &klog_once)) {Odd whitespace...
Anyway, why? Isn't this what the ratelimit stuff should give you? How badly is this being tripped so much so that you need to only do this once per entire system and not per-device?
The problem with "v1" was that the message was printed once, but the dump_stack() was called however many times. And ratelimited stuff is afaik only for printk's, there's no ratelimited dump_stack().
What you're saying makes sense tho. It would be sane behaviour to do this once-per-device, instead of just once.
Since struct tpm_chip already has a bitmask flags, I'll just add a TPM_CHIP_FLAG_INVALID_STATUS, and:
if (test_and_set_bit(TPM_CHIP_FLAG_INVALID_STATUS, &chip->flags)) { /* ... */
thanks,
greg k-h
Thank you.
/Jarkko
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